Absorption-cycle refrigerating unit

ABSTRACT

An absorption-cycle refrigerating unit, comprising an electrically heated boiler, covered with a layer of mineral wool that is covered by an external enclosure made of expanded plastic material.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an improvement to anabsorption-cycle refrigerating unit.

[0002] As is known, in absorption-cycle refrigerating units therefrigeration fluid is generally constituted by a mixture of water andammonia that is heated in a boiler by way of the heat provided by anelectrical resistor. The generated heat causes the evaporation of theammonia, which separates from the water. As evaporation proceeds, thepressure increases until it is high enough to cause the condensation ofthe ammonia. According to what occurs in compression-cycle refrigeratingunits, the ammonia, through a valve, then expands in an evaporator,returning to the gaseous state and drawing heat from the surroundingenvironment (the inside of a refrigerator). The water, which nowcontains small quantities of ammonia, passes from the boiler into theabsorber, through a heat exchanger, to which it transfers part of itsheat. Here it mixes with the pure ammonia vapor that arrives from theevaporator and becomes saturated. A circulation pump returns the mixtureof ammonia and water to the boiler through the heat exchanger, where themixture absorbs the heat of the water that arrives from the boiler. Thecycle can therefore resume in the described manner.

[0003] As is evident, in order to maintain a high efficiency ofabsorption-cycle refrigerating units it is crucial to limit the heatlosses of the boiler and increase its efficiency.

SUMMARY OF THE INVENTION

[0004] The aim of the present invention is therefore to improve anabsorption-cycle refrigerating unit that allows to achieve a higherinflow of calories to the boiler and therefore reduce the time requiredby the unit to reach the intended operating temperature, withcorresponding triggering of the power-off device, or allows to use aless powerful electric resistor.

[0005] Within this aim, an object of the present invention is to providean assembly in which the improvements that have been introduced have noappreciable effect on the cost standpoint of the unit.

[0006] This aim and this object are achieved according to the presentinvention with an absorption-cycle refrigerating unit, comprising anelectrically heated boiler, characterized in that said boiler is coveredwith a layer of mineral wool that is covered by an external enclosuremade of expanded plastic material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Further features and advantages of the present invention willbecome better apparent from the description that follows of a preferredembodiment, illustrated only by way of non-limitative example in theaccompanying drawings, wherein:

[0008]FIG. 1 is a perspective view of an absorption-cycle refrigeratingunit;

[0009]FIG. 2 is a front elevation view of the unit of FIG. 1 with theboiler shown in cross-section;

[0010]FIG. 3 is a sectional view, taken along the line III-III of FIG.2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] With reference to the figures, the reference numeral 1 generallydesignates an absorption-cycle refrigerating unit. Unit 1 comprises, asdescribed initially, a boiler 2, whose output is connected to acondenser 3. The output of the condenser 3, through an expansion valveor choke (not shown), is connected to an evaporator 4, whose output isin turn connected to an absorber 5.

[0012] The reference numeral 6 designates a tank for collecting therefrigeration mixture, in which the input is connected to the output ofthe absorber 5 and the delivery is connected to the input of the boiler2. The circuit contains a gas (helium) under pressure, which allows tocontrol the cycle of the refrigeration fluid.

[0013] The boiler 2, the condenser 3, the absorber 5 and the tank 6 aremounted externally with respect to the space to be refrigerated(refrigeration cell) and in which the evaporator 4 is located.

[0014] In the continuation of the description, the connections among thevarious components are not described, since they are fully conventionaland unrelated to the present invention, whose particularities reside inthe structure of the boiler.

[0015] As clearly shown in FIGS. 1 to 3, the boiler 2 is constituted bya tubular element or sleeve 7 that lies vertically between the tank 6and the condenser 3. A heating body is fixed thereon and is constitutedby an electrical resistor 8 that is powered by means of conductors 9.Advantageously, the electrical resistor 8 has a semicylindrical shapethat allows to surround a large region of the tubular element 7. Thisprovides a wide surface of contact between the tubular element 7 and theresistor 8, which ensures greater heat exchange while containing thediametrical dimensions of the heating element and therefore the spaceoccupation.

[0016] A layer 10 of thermally insulating material, for example made ofmineral wall such as rock wool or glass wool, is arranged around theelectrical resistor 8 and, if appropriate, around the tubular element 7.

[0017] Conveniently, the tubular element 7 is covered along its entirelength by an additional layer of thermally insulating material, whichconsists of an enclosure 11 made of expanded plastic material.Preferably, said material is an expanded polyurethane, which is capableof providing an effective barrier against the irradiation of heat andtherefore constitute an effective thermal protection for the nearbycomponents.

[0018] It should be noted that the thermally insulating layer 10 ofmineral wool also ensures an effective protection for the polyurethaneenclosure 11, protecting it against excessive temperatures at theelectric resistor 8.

[0019] It is evident that the described improvement allows to achievethe intended aim and object. In particular, the arrangement of the layer10 and of the enclosure 11 has allowed to reduce significantly theconsumption of electric power. According to tests that have beenconducted, the energy saving can be quantified as on the order of 20%with respect to the consumption of refrigerating units currently in use.

[0020] The described refrigerating unit 1 is susceptible of numerousmodifications and variations, all of which are within the scope of thesame solution idea. In a preferred embodiment, the enclosure 11 made ofexpanded plastic material is prism-shaped, with a quadrangularcross-section that allows to better utilize the space around the tubularelement 7.

[0021] In another embodiment, the boiler 2 is accommodated in a metallicbox-like body for containing the enclosure 11 made of plastic material.

[0022] In the practical execution of the invention, the shapes and thedimensions may be any according to requirements.

[0023] The disclosures in Italian Patent Application No. BO2001A000613from which this application claims priority are incorporated herein byreference.

What is claimed is:
 1. An absorption-cycle refrigerating unit,comprising: an electrically heated boiler, a layer of mineral wool thatcovers said boiler; and an external enclosure made of expanded plasticmaterial which covers said layer of mineral wool.
 2. The refrigeratingunit of claim 1, wherein said external enclosure is made of expandedpolyurethane.
 3. The refrigerating unit of claim 1, wherein said boileris constituted by a tubular element, a heating body fixed on saidtubular element, said heating body being constituted by an electricresistor that has a semicylindrical shape and is provided so as tosurround a region of said heating body.
 4. The refrigerating unit ofclaim 2, wherein said enclosure made of expanded plastic material has aprism-like quadrangular cross-section.
 5. The refrigerating unit ofclaim 4, further comprising a metallic box-like body which contains saidenclosure made of expanded plastic material.